Effective Spinless Fermions in the strong-coupling Kondo Model

Starting from the two-orbital Kondo-lattice model with classical (formula presented) spins, an effective spinless fermion model is derived for strong Hund coupling (formula presented) with a projection technique. The model is studied by Monte Carlo simulations and analytically using a uniform hopping approximation. The results for the spinless fermion model are in remarkable agreement with those of the original Kondo-lattice model, independent of the carrier concentration, and even for moderate Hund coupling (formula presented) Phase separation, the phase diagram in uniform hopping approximation, as well as spectral properties including the formation of a pseudogap are discussed for both the Kondo-lattice and the effective spinless fermion model in one and three dimensions.